In a method of obtaining an image by an electrophotographic printing method or an electrostatic charge developing method, an electrostatic charge image formed on a photoreceptor is developed with a toner charged by friction in advance and then fixed. In this process, the toner is required to firstly maintain a stable electric charge amount and to secondly exhibit fixability to the paper.
In addition, an apparatus to be used for obtaining an image by an electrophotographic printing method or an electrostatic charge developing method has a fixing section of a heating member, the temperature in the apparatus thus increases, and the toner is thus required not to block, namely, to exhibit storage stability.
Particularly in the fixing method using a heat roller, a decrease in temperature of the fixing section has been progressed from the viewpoint of energy saving, and the toner has been thus strongly required to exhibit low temperature fixability. In addition, a roller which is not coated with oil has been used as miniaturization of the apparatuses has been progressed, and the toner has been highly required to exhibit releasability from the heat roller, namely, non-offset property.
It is also required that dirt on the apparatus even at the time of continuous printing and fogging at the time of printing are not observed, that is, durability of the toner is required.
A binder resin for toner greatly affects the toner properties as described above, and a polystyrene resin, a styrene acrylic resin, a polyester resin, an epoxy resin, a polyamide resin, and the like are known. Recently, a polyester resin has particularly attracted attention since it exhibits excellent storage stability, low temperature fixability, non-offset property, durability, pulverizability at the time of production of toner, and the like and exhibits performances in a favorable balance.
For example, Patent Literature 1 proposes a toner exhibiting excellent low temperature fixability, hot offset resistance, glossiness, durability, and storage stability.
On the other hand, in recent years, a carbon neutral strategy has particularly attracted attention from the viewpoint of environmental protection such as suppression of global warming, and it has been actively attempted to change plastics derived from conventional petroleum raw materials to plastics derived from vegetable raw materials with lower environmental impact. The use of components derived from vegetable raw materials in toner is also investigated.
For example, Patent Literatures 2 and 3 propose a toner using a binder resin for toner containing a raw material component derived from vegetables.